Multiscale nanocelluloses hybrid aerogels for thermal insulation: The study on mechanical and thermal properties

Herein, multiscale nanocelluloses (NCs) were prepared and blended with fumed silica and organosilane to fabricate freeze-dried aerogels in various combinations. The cooperation of multiscale raw materials optimized the porous structures of aerogels, thus improving the thermal insulation properties. The use of NCs with different characteristics endowed the resultant aerogels with distinct mechanical performance. The addition of high-aspect-ratio NCs in the composite aerogels was essential for improving the bendability. Furthermore, lower-aspect-ratio NCs helped to resist the compression deformation of the cross-linked aerogels. The functional groups on NCs made a difference in the thermal stability of the as-prepared aerogels. However, after treating at 150-350 ℃, the aerogels could maintain structural integrity and high elastic recovery rate, possessing ultralow density (7.2 kg/m³) and thermal conductivity (25.4 mW m^-1 K^-1). The outstanding thermal properties and controllable mechanical performance make these aerogels potential candidates in different fields such as textile and building industries.